1. Field of the Invention
This invention relates to: (a) a method for preparing a concentrated, liquid smoke from a tar-depleted, liquid smoke solution, (b) tar-depleted, concentrated liquid smoke compositions, (c) food casings colored and flavored with tar-depleted, concentrated, liquid smoke compositions, (d) a method for preparing a smoke colored and flavored foodstuff encased in a casing, (e) a method for neutralizing a tar-depleted, concentrated liquid smoke, and (f) tar-depleted, concentrated, partially neutralized liquid smoke compositions.
2. Description of the Invention
Tubular cellulosic food casings are used extensively for processing a great variety of meat products and other food items. The food casings are generally thin-walled tubing of various diameters prepared from reconstituted materials, such as regenerated cellulose. Cellulosic food casing may also be prepared with fibrous webs embedded in the wall thereof, such casings commonly being referred to as "fibrous food casings."
The many different recipes and modes of processing that are used by the processed food industry to suit different tastes, and even regional preferences, generally necessitate the use of food casings with a variety of characteristics. In some instances, for example, food casings are required to have multifunctional uses wherein they serve as containers during the processing of a food product encased therein, and then also serve as a protective wrapping for the finished product. In the processed meat industry, however, the food casings used in the preparation of many types of meat products, such as various types of sausages, such as frankfurters, bolognas and the like, beef rolls, hams and the like, are frequently removed from about the processed meat product prior to slicing and/or final packaging.
Surface appearance and flavor are important factors in the commercial and consumer acceptance of processed meat products, and a common feature of most varieties of such products involves the use of "smoking" for imparting characteristic flavor and color thereto. The "smoking" of food products is generally accomplished by the food processor subjecting the food product to actual contact with smoke in a gaseous or cloud-like form. Such "smoking" processes, however, have not been considered completely satisfactory for a variety of reasons, including the inefficiencies and lack of uniformity of the "smoking"operation. Because of the shortcomings experienced, many meat packers now employ various types of liquid aqueous solutions of wood-derived smoke constituents, commonly called "liquid smoke solutions" that have been developed and used commercially in the food processing industry for the processing of many types of meat and other food products. For convenience in this specification, these commercially available "liquid smoke" solutions in their as-purchased state will be frequently referred to herein as "as-is" liquid smoke.
The application of "liquid smoke solutions" to meat products is generally carried out in a variety of ways, including spraying or dipping an encased food product during the processing thereof, or by incorporating the "liquid smoke solution" in the recipe itself. The actual operation of "smoking" by spraying or dipping is not completely satisfactory due to inability to treat the encased product uniformly, and incorporation of "liquid smoke solution" in the meat recipe does not always provide the desired surface appearance because of dilution of smoke ingredients. Incorporation in the recipe also reduces the stability of the meat emulsion, and will adversely affect taste if high concentrations are used. Application of liquid smoke to encased food products by the food processor, such as by spraying or dipping, also causes unwanted pollution and equipment corrosion problems for the food processor. In addition, encased sausages treated by application of the liquid smoke during commercial processing have been found to yield, after peeling the casing from the treated encased food product, sausages which are lacking in smoke color uniformity from sausage to sausage, and from batch of sausages to batch of sausages. What is even more undesirable is the lack of uniformity of coloration which often appears on the surface of the individual sausages, including light and dark streaks, light and dark blotches, and even uncolored spots which especially appear at the ends of sausages.
Several methods are known for coating either the interior or the exterior of a food casing with various liquid substances designed to meet particular processing requirements, as, for example, substances that affect the adhesion properties of the casing. Some of the coatings known in the art contain a liquid smoke as a constituent thereof. However, none of these coatings applied to sausage casings have been known to impart smoke color and flavor to the food product to a suitable extent.
Known methods for coating an "as-is" type of liquid smoke solution internally in a casing have been found to be costly and also have been found to limit the speed of a continuous high speed production line.
Known methods for coating the external surface of a casing, particularly a cellulosic gel-stock casing, with "as-is" type liquid smokes, result in problems due to the tar content of these smoke solutions. That is, during the coating process, tarry deposits accumulate on the carrier rolls and the squeeze rolls of the treatment unit, which eventually forces shutdown of the treatment system.
One solution to the above mentioned problems of imparting smoke color and flavor to a foodstuff is to use "tar-depleted" liquid smoke solutions to coat the interior or, preferably, the exterior surface of the casing. However, until recently, tar-depleted liquid smoke solutions were unavailable, and methods for making the same were unknown. As indicated above, it has been found that when a cellulosic food casing, made from a fibrous or non-fibrous gel stock, is treated with a highly acidic (pH of about 2.0 to 2.5) tar-containing, aqueous liquid smoke, tarry deposits accumulate on the carrier rolls and the squeeze rolls of the smoke treatment unit, causing the casing to stick to the rolls and eventually forcing shutdown of the unit. The acidity of the liquid smoke also may interfere with peelability of the casing by interfering with the action of the peeling aid used, such as, for example, carboxymethyl cellulose. Aqueous liquid smokes are generally very acidic, having a pH of 2.5 or less and a titratable acidity of at least 3 weight percent.
It was found that tar could be removed from the liquid smoke by neutralizing the as-is liquid smoke to precipitate the tar, and that use of this neutralized, tar-depleted liquid smoke to treat a gel stock casing would eliminate the tarry deposit accumulation problem. This is disclosed in copending U.S. patent application Ser. No. 417,172, filed 14 Sept. 1982 by Nicholson now U.S. Pat. No. 4,431,032.
Contrary to the previous belief in the art, the tar-depleted liquid smoke still possesses significant smoke coloring and flavoring capability. It has been generally believed that the tars in a liquid smoke mainly contribute to the coloring and flavoring ability of the liquid smoke. However, it has been found that this is not the case, and that other constituents of the liquid smoke, believed to be mainly the acids, the phenols and the carbonyls, have a more significant role in the coloring and flavoring ability of the liquid smoke.
One problem with the neutralizing method for forming a tar-depleted liquid smoke is that, although the liquid smoke compositions made thereby have significant coloration ability or "staining power", the coloration ability declines with increasing pH or neutralization. This limits its applicability in applications wherein a high coloration ability is desired.
Another method, using a "solvent extraction" process, may be employed to make tar-depleted liquid smoke. Such a process is disclosed in copending U.S. patent application Ser. No. 417,173, filed 14 Sept. 1982 by Nicholson now U.S. Pat. No. 4,431,033. For example, such a process comprises contacting a tar-containing aqueous smoke solution having an absorptive power of at least about 0.25 at a wave length of about 340 nm, with either a nonreactive or reactive organic liquid solvent which has a hydrogen bonding solubility parameter of at least about 2.7 and which is immiscible in the aqueous liquid smoke solution under conditions sufficient to form a tar-enriched solvent fraction and a tar-depleted liquid smoke fraction, and separating the liquid smoke fraction to form a tar-depleted liquid smoke. Using such a solvent extraction method, it becomes possible to make tar-depleted liquid smokes having a high capability to impart smoke color, odor, and flavor, without requiring neutralization of the tar-containing liquid smoke.
The tar-depleted liquid smoke made from the solvent extraction process, unless it is neutralized, is generally highly acidic, which may also interfere with action of the peelability agents, such as certain water soluble cellulose ethers, which may be used on the casing. To alleviate this problem, the tar-depleted liquid smoke may be partially neutralized. However, since the coloration ability of the liquid smoke declines with increasing pH, the tar-depleted liquid smoke is only "partially neutralized" to a degree such that the peelability agent is not significantly affected and the coloration ability of the smoke is retained. The term "partially neutralized", as used herein, is intended to refer to liquid smoke compositions having a pH greater than about 3, preferably having a pH within the range of from about 3 to about 6.5, and even more preferably having a pH within the range of from about 3 to about 5. By providing a partially neutralized, tar-depleted liquid smoke made from a solvent extraction process, the problems due to acidity are avoided while retaining a significant degree of the coloring ability of the original as-is liquid smoke.
Unconcentrated liquid smoke compositions, whether partially neutralized or unneutralized, have been found particularly suitable for use with fibrous cellulosic food casings. When used with nonfibrous casings, it has been found that unconcentrated liquid smokes impart a smoke color, odor and flavor to the foodstuff, but not in a quantity to be sufficiently acceptable for all commercial applications. Because nonfibrous casings are thinner than fibrous casings, sufficient unconcentrated liquid smoke cannot be "coated" on, applied to, or incorporated in the wall of the casing to an extent sufficient to always impart the desired smoke color, odor and flavor to a foodstuff.